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Table 1 Comparison of the screening methods for metagenomeic libraries

From: Screening for novel enzymes from metagenome and SIGEX, as a way to improve it

  Function-based screening Sequence-based screening SIGEX
Screening principle • Detecting changes by enzymatic reactions (e.g. halo formation around the colonies) • PCR or Southern hybridization based on the DNA sequence consensus • Trapping the operon induced by a substrate and sorting using FACS
Advantages • Secures a complete form of gene or gene cluster required for desired traits
• Potentially obtains completely novel genes.
• Overcomes the limitations of the heterologous expression • Fast and economical
• Any substrates that can be introduced into cytoplasm can be used in its native forms.
Disadvantages • Must satisfy the expression conditions (transcription, translation, folding, secretion) in heterologous hosts • Requires a database and analyses of the DNA sequence consensus.
• Does not guarantee the acquisition of complete forms of genes or gene clusters.
• Sensitive to the orientation of the genes with desired traits
• Cannot use substrates that do not migrate to cytoplasm
• Sensitive to the initial FACS setting
Examples antibiotics [9, 19-22], genes involved antibiotic resistance [9, 23, 24], agarases [15], amidases [13], amylases [15, 21, 25, 26], esterase/lipases [8, 15, 21, 27, 28], xylanases [29], 4-hydoxybutyrate dehydrogenase [30] alcohol oxidoreductases [14], pectate lyases [31] amylases [26], polyketide synthases [32, 33] Benzoate-degratative or catechol degradative operon, P450 enzyme [16]